The present embodiments relate to phase change or solid ink compositions characterized by being solid at room temperature and molten at an elevated temperature at which the molten ink is applied to a substrate. These solid ink compositions can be used for ink jet printing. The present embodiments are directed to a novel solid phase change ink composition comprising a crystalline oxazoline compound, an amorphous component that is derived from polyols, and optionally a colorant, and methods of making the same.
Solid phase change inks (also referred to as “phase change inks” and “hot melt inks”) have been used in various liquid deposition techniques. Solid phase change inks are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the recording substrate, either directly or via an intermediate heated transfer belt or drum, they quickly solidify to form a predetermined pattern of solidified ink drops. Phase change inks have also been used in other printing technologies, such as gravure printing, as disclosed in, for example, U.S. Pat. No. 5,496,879 and German Patent Publications DE 4205636AL and DE 4205713AL, the disclosures of which are totally incorporated herein by reference.
Solid inks have also been used for applications such as postal marking, industrial and office marking, labeling, and for rapid 3-dimensional prototyping of objects.
Solid inks are desirable for ink jet printers because they remain in a solid phase at room temperature, for example, 20° C. to about 35° C., which is convenient during shipping and ink handling, enables long term storage, and ease of use. In addition, the problems associated with nozzle clogging as a result of ink evaporation with other aqueous or solvent-based liquid ink jet inks are largely eliminated, thereby greatly improving the reliability of the ink jet printing. Further, in solid ink jet printers wherein the ink droplets are applied directly onto the final recording substrate (for example, paper, transparency material, and the like), the droplets solidify immediately upon contact with the substrate, so that migration of ink along the printing medium is prevented and image quality is improved.
Ink jet printing systems generally are of two types: continuous stream and drop-on-demand, as described in U.S. Pat. No. 6,547,380. The entire disclosures of U.S. Pat. Nos. 5,195,430 and 6,547,380 are totally incorporated herein by reference.
There are at least three types of drop-on-demand ink jet systems. One type of drop-on-demand system is a piezoelectric device that has as its major components an ink filled channel or passageway having a nozzle on one end and a piezoelectric transducer near the other end to produce pressure pulses. Another type of drop-on-demand system is known as acoustic ink printing. Still another type of drop-on-demand system is known as thermal ink jet, or bubble jet, and produces high velocity droplets.
In a typical design of a piezoelectric ink jet device utilizing solid inks, whether printed directly onto a substrate or onto an intermediate transfer member, such as the ones described in U.S. Pat. Nos. 5,372,852; 7,063,410; and 7,448,719 the disclosures of which are hereby incorporated by reference in their entireties, droplets of liquid ink are ejected from the printing device at the printhead operating temperature. When the ink droplets contact the surface of the recording substrate, either directly or via an intermediate heated transfer belt or drum, they rapidly solidify to form a predetermined pattern of solidified ink drops.
Many solid inks typically used with ink jet printers are comprised of (semi)crystalline and polymer waxes as part of the ink vehicle (or ink base). Crystalline waxes and other functional wax components enable the sharp melting of the ink and narrow phase-change transitions from the molten liquid state to the solid state. The wax components also reduce the coefficient of friction of the printed image, which aids the automated feeding of printed documents across the glass platen and other subsystems of the printer. Such wax-based, solid ink jet inks provide vivid color images.
In typical systems, these crystalline wax inks partially cool on an intermediate transfer member and are then pressed into the image receiving medium such as paper. Transfuse action spreads the image droplet, providing a richer color and lower pile height. The low flow of the solid ink also prevents show through on the paper.
However, the use of crystalline waxes can pose some limitations on the printed image. Conventional crystalline waxes are non-polar hydrocarbon polymers and aliphatic molecules, which are attracted together by weak, non-covalent van der Waals forces. Such waxes typically have poor adhesion to paper substrates because there is low affinity for the higher polarity paper. This mismatch of intermolecular forces and polarity between ink and substrate can make the wax-based solid prints vulnerable to mechanical damage, such as abrasions and creases, which can lead to poor image robustness and lower image quality. Further, the nonpolarity of these ink components often leads to compatibility issues with commonly available commercial dyes and pigments, resulting in the need for custom-designed colorants to ensure good solubility or dispersibility in the ink carrier and good long-term thermal stability to prevent colorant degradation or colorant migration. There is consequently a need for new solid ink compositions having higher polarity than wax-based inks and that have good affinity for a wide variety of paper substrates. There is also a need for new solid ink compositions of higher polarity and good compatibility with commercially available colorants and ink additives. There is furthermore a need for such new ink compositions to have improved durability on paper substrates compared with wax-based solid inks.
Oxazolines are a promising class of heterocyclic compounds which have been previously reported for medical, pharmaceutical, and veterinary uses, and also as additives in personal care and consumer product formulations, such as shampoos, detergents, and the like, and in oleaginous compositions such as mechanical lubricating oils and as oil and sludge dispersants. Oxazolines can be prepared efficiently in one or more reaction steps from simple starting materials, which are typically an organic carboxylic acid and a primary amino alcohol. Detailed reviews of the chemistry of oxazoles and oxazoline compounds are known, as illustrated by R. H. Wiley and L. L. Bennett in Chemical Reviews, Vol. 44, pp. 447-476 (1949), and also extensively described by J. W. Cornforth in Heterocyclic Compounds, 1957, chapter 5, pp. 300-417, the disclosures of each of which are totally incorporated herein by reference. Furthermore, oxazoline derivatives being the major product from the reaction of an organic acid and amino alcohol is also known, such as disclosed by A. I. Meyers and D. L. Temple in Journal of the Chemical Society, Vol. 92, p. 6644 (1970), the disclosure of which is totally incorporated herein by reference. Further, in Garrett C. Moraski et al. in European Journal of Medicinal Chemistry, 45, (2010), 1703-1716, the disclosure of which is totally incorporated herein by reference, there is described low toxicity anti-tuberculosis agents derived from o-hydroxy phenyl-oxazoline and o-hydroxy phenyl-oxazole benzyl esters.
While known materials and processes are suitable for their intended purposes, there is a need for improved phase change inks. In addition, there is a need for phase change inks that exhibit sharp and rapid phase transitions from the molten liquid state to the solid state. Further, there is a need for phase change inks that exhibit good adhesion to paper substrates, including coated and uncoated paper substrates. Additionally, there is a need for phase change inks that exhibit good image robustness, such as scratch-resistance. In addition, a need remains for phase change inks that exhibit good ‘paper fold’ performance and reduced cracking and creasing of the image when the document is folded. Additionally, a need remains for phase change inks that exhibit good compatibility with commonly available colorants. In addition, there is a need for phase change inks that are suitable for ink jet printing under a variety of conditions, such as direct-to-paper (DTP) printing conditions. Further, there is a need for phase change ink compositions prepared from low-cost raw materials, that are compatible with a wide variety of papers that generate high quality images on a wide variety of papers. These and other needs and advantages can be achievable with the solid ink compositions comprising crystalline oxazoline compounds and amorphous compounds derived from polyols of the present disclosure.
Each of the foregoing U.S. Patents and Patent Publications are incorporated by reference herein. Further, the appropriate components and process aspects of the each of the foregoing U.S. Patents and Patent Publications may be selected for the present disclosure in embodiments thereof.